Plate IV. 

 External appearance of Teras XX. 

 Fig. 1. Dorsal view. 

 Fig. 2. Ventral view. 

 Fig. 3. Ventral view, plastron reraoved. 



a., Anlage of median pair of fore limbs ; b., Anlage of median double 

 shoulder girdle ; c, Right epicorocoid cartilage ; c'., Left epicorocoid cartilage ; 

 u., Umbilicus ; x, Region of doubling of the anterior plates of the carapace ; 

 y, Region of doubling of the anterior plates of the plastron. 



